The relevant prior art is noted to include U.S. Pat. No. 4,096,202 wherein disclosed are blends of polyalkylene terephthalate containing a crosslinked acrylic phase based multiphase composite characterized in its improved impact strength. U.S. Pat. No. 3,864,428 is noted to disclose impact improvement to an aromatic polyester molding composition containing a certain graft copolymer of a butadiene polymer vinyl monomer.
Core shell polymeric compounds having a butadiene-based core are taught in U.S. Pat. No. 4,180,494 to improve the impact performance of compositions comprising an aromatic polyester and an aromatic polycarbonate. Also of relevance is U.S. Pat. No. 3,769,260 wherein disclosed are thermoplastic molding compositions containing linear saturated polyesters and certain .alpha.-olefin polymer. Blocked (capped) polyurethanes of the type useful in the present context have been disclosed in U.S. Pat. No. 4,292,226.